End stage renal disease (ESRD) is a medically, socially, and economically devastating reality for over 172,000 patients in the United States. The average per capita cost of treatment was $35,600, for an aggregate total of $5.4 billion in 1988. Most patients receive treatment in a dialysis center setting. The cost for home-care patients is approximately half that for dialysis center patients. In addition to substantially lowering costs for ESRD treatment, a portable artificial kidney will improve quality of life for many patients by freeing them from a center dependent lifestyle. The ultimate goal of this research program is development of a truly portable electrochemical artificial kidney which uses a minimal amount of dialysate, about 5 L per hemodialysis session, in the maintenance of patients with end stage renal disease (ESRD). In principle, the proposed artificial kidney requires little more than an electrical outlet and tap-water source for its operation. The specific objective of this proposal is development and performance validation of the electrochemical dialysate regeneration system that will be used in the portable artificial kidney, specific research objectives include: determination of breakthrough curves and appropriate size for a clinical scale zeolitic ammonia absorption column; construction of a clinical-scale electrochemical dialysate regeneration system comprised of an electrochemical oxidation reactor and ammonia absorption column; demonstration of the efficacy of the system in removal of such waste metabolites as urea, uric acid, creatinine from dialysate; demonstration of the efficacy of the system in conjunction with in vitro dialysis with limited quantities (about 5 L) of recycled dialysate; monitoring of hemodialysis backexchange of reaction products to the in vitro simulated patient; and determination of the nature of such products. The specific aims will be accomplished through a laboratory investigation using electrochemistry, wet chemistry, and dialysis apparatus. Statistically designed experiments to maximize information for effort expended will be used. The major results from successful completion of this proposal are demonstration that a compact electrochemical approach to dialysate regeneration for use in portable hemodialysis applications is feasible and demonstration that zeolitic ammonia absorption is an alternative, potentially superior approach to the commonly used zirconium oxide/zirconium phosphate ion exchange for ammonia removal in dialysate regeneration.